Question

The letter T in T-lymphocytes refers to
(a) Thymus
(b) Thyroid
(c) Thalamus
(d) Tonsil

Answer 1

Hint: It is found within the upper front, a part of the chest, within the anterior superior mediastinum, behind the sternum, and ahead of the heart. It is also called the ‘Throne of immunity’ or ‘training schools of T-lymphocytes.’

Complete answer:
A type of lymphocyte is a T cell. The T cell is derived from the National Institutes of Health (2016) hematopoietic stem cells. The T cell matures in the thymus gland (hence the name) and plays a central role in the immune response, which is located in the bone marrow. The presence of a T-cell receptor on the cell surface may differentiate T cells from other lymphocytes. These immune cells emerge as bone marrow-derived precursor cells and, once they have migrated to the thymus gland, grow into many distinct forms of T cells. And after they have entered the thymus, T cell differentiation proceeds. By supplying a range of immune-related functions, groups of unique, differentiated T cells play an important role in regulating and influencing the immune response. One of these functions is immune-mediated cell death, and T cells perform it in many ways: CD8+ T cells, also referred to as "killer cells" are cytotoxic, which means they can kill virus-infected cells as well as cancer cells directly.

Additional information:
In the upper front of the lung, in the anterior superior mediastinum, behind the sternum, and in front of the heart, the thymus is located. It is made up of two lobes surrounded by a capsule, each consisting of a central medulla and an outer cortex.
The thymus is made up of immature T cells called thymocytes, as well as epithelial cells called lining cells that help grow the thymocytes. T cells that grow successfully respond properly with the body's MHC immune receptors (called positive selection) and not against the body's proteins called negative selection). In the neonatal and pre-adolescent ages, the thymus is the strongest and most active. The thymus starts to decline in size and activity by the early teens, and the tissue of the thymus is eventually replaced by fatty tissue. Nevertheless in adult life, some T cell growth occurs.

So, the correct answer is ‘Thymus’.

Note:
For cell-mediated immunity, T lymphocytes, or T cells, are responsible. T cells come with particular roles in many ways, including Helper T cells guide the immune system. Helper T cells release cytokines in a very lengthy process. In order to form plasma cells, cytokines activate B cells.